- silly (adj.)
- Old English gesælig "happy" (related to sæl "happiness"), from West Germanic *sæligas (cf. Old Norse sæll "happy," Gothic sels "good, kindhearted," Old Saxon salig, Middle Dutch salich, Old High German salig, German selig "blessed, happy, blissful"), from PIE root *sel- "happy" (cf. Latin solari "to comfort").
The word's considerable sense development moved from "blessed" to "pious," to "innocent" (c.1200), to "harmless," to "pitiable" (late 13c.), to "weak" (c.1300), to "feeble in mind, lacking in reason, foolish" (1570s). Further tendency toward "stunned, dazed as by a blow" (1886) in knocked silly, etc. Silly season in journalism slang is from 1861 (August and September, when newspapers compensate for a lack of hard news by filling up with trivial stories). Silly Putty trademark claims use from July 1949.